Why have sex? Why not!

Why do people have sex? Ask an evolutionary biologist and you'll get a lot of answers: After all, bacteria and yeast and many plants can just spit off new versions of themselves, so biologists have been debating for years why sex and sexes evolved. Now it turns out that if you ask a bunch of men and women why they, personally, like to have sex you'll also get a slew of reasons: 237, to be precise.

David Buss and Cindy Meston, psychologists at the University of Texas at Austin, discovered this after asking 400 men and women (in one study) and 1,500 undergraduates (in another) why they have sex.

Here's some of the reasons offered up: "It's exciting," "My partner kept insisting," "I was curious" and "The person was a good dancer."

And these: "I was bored," "I wanted to get a promotion," "It seemed like good exercise" and "I wanted to feel closer to God."

Still more: "I wanted to give someone a sexually transmitted disease" and "I wanted to keep my partner from straying."

And even this one: "I wanted to have a baby."

The study, published in the August issue of the journal Archives of Sexual Behavior, grouped the 237 reasons into four major categories (physical reasons, goal-based reasons, emotional reasons and insecurity-based reasons.). "Why people have sex is extremely important, but rarely studied," Buss says in a press release.

Want to learn more about sex and why it's fun? Check out the book "Why Is Sex Fun?" by UCLA biologist and writer Jared Diamond. (Read all about it at www.amazon.com/Why-Sex-Fun-Evolution-Sexuality/dp/0465031269).